A precision structural system carrying a load, such as a telescope, may be susceptible to disturbances that produce structural vibrations. Such vibrations may be contributed to the structural system by components or assemblies, such as reaction wheel assemblies that are used to point the system vehicle. For the most part, because these systems tend to not have inherent damping mechanisms, these structural vibrations may cause degradation of the system and system performance over time. Therefore, an efficient means of damping the system may be needed.
Typically, to minimize performance degradation caused by vibrations, a passive mass damping and isolation system has been used for damping and isolating the lad carried by a precision isolation system. One type of passive mass damping and isolation system is a fluid damper. Fluid dampers operate by displacing a viscous fluid from one fluid reservoir to another fluid reservoir through a restrictive passage. Shearing of the viscous fluid as it flows through the restrictive passage provides a damping force that is proportional to velocity.
In these types of dampers, the viscous fluid is typically water, oil, or any one of numerous other fluid substances that are not in the gas, plasma, or solid phase. Although these fluids may be used in damping mechanisms that operate in environments where the fluid temperature is in liquid phase temperature range, once the fluid deviates out of this range, the fluid can begin to change state. For instance, in the aerospace context where damping mechanisms may be exposed to temperatures that approach 0° Kelvin, most of the fluids used in fluid dampers lose viscosity and/or phase change from a fluid to a solid.
In other types of dampers, such as pneumatic fluid mass dampers, fluids such as gases, are used. Pneumatic fluid mass dampers operate by varying pressure, temperature and gas viscosity. However, in the aerospace context at 0° Kelvin, gas to liquid phase changes may occur. Such changes are generally undesirable because when the gas changes into a liquid, the resulting volume of liquid and gas may not adequately absorb the system vibration and instead may begin to vibrate itself.
Accordingly, there is a need for an improved vibration damping system that can be used in most temperature ranges, and in particular in extreme cryogenic temperature environments, such as 0° Kelvin or extreme heat environments. In addition, it is desirable to maintain a weight, size, and complexity efficient structure, as well as improve the integrity of the structure. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.